1. Field of the Invention
This invention relates generally to an adaptor for quickly and easily securing prescription eyeglass lenses to a frame. More particularly, the present invention is directed to an adaptor to be affixed to an eyeglass lens, and received in an eyeglass frame, to facilitate the fitting and replacement of complex-shaped prescription lenses to an eyewear frame.
2. Background Discussion
A typical pair of eyeglasses includes a pair of lenses or a single shield mounted to a frame that may include rims around the lens or lenses; a brow bar; a bridge piece or nose bridge connecting the inner ends of the rims or lenses; and two temple pieces attached to the outer ends of the rims or lenses for resting the glasses on the user. Typical full-rim frames have rims with one or more breaks in the rim with the free ends adapted to accept a threaded fastener such as a screw. Lenses are typically mounted in such eyeglass frames by using the screw or other fastening device to draw the free ends of the split frame together, thus tightening the rim around the lens. In the conventional configuration, the screw must be removed before the lens may be removed. Because of the size of the screw, the variety of screw configurations used in the field, the installation and removal tools required, and the specialized knowledge and skill required to properly replace a lens, removal and replacement of lenses is beyond the ability of the typical eyeglass wearer.
Eyewear designs have been directed to eyewear frames in which the lenses can be secured to the frame without resorting to a continuous rim, or with no rim at all, generally referred to as rimless frames. One type of rimless frame, the wing style, typically includes a brow bar, a temple piece secured to each end of the brow bar, and either a single shield or two separate lenses attached to the brow bar. The wing style frame can provide the appearance of the lenses being suspended from the brow bar, evoking a desirable athletic or sporty look. Because the wing style frame secures the lenses from the brow bar only, improved peripheral vision is achieved. Lenses used with wing style frames can be secured to the brow bar permanently with any known mechanical means or adhesive systems. The lenses may also be temporarily secured with an interacting system of mechanical components such that the lenses can be easily replaced in the frame. The mechanical components can be appropriately shaped recesses in the frame, shaped to accept notches on the lens, posts to interact with the notches, keyhole slots and co-acting T-shaped posts, snap fit components, barbed fittings, or any other co-acting fastener system known in the art. Additionally, magnets or magnetic material may be affixed to the lenses and/or the brow bar to removably attach the lenses to the frame. Such simple interlock or attachment mechanisms require no special tools to remove or install lenses. No special skill is needed in order to interchange the lenses, making the lenses replaceable by the typical wearer.
Another style which does not require a rim to secure the lens is known as the three-piece mount. In this style, the lenses are a structural component of the eyewear and no brow bar is needed. Temple pieces are secured directly to the lenses at an outer edge. A nose bridge is secured between the lenses adjacent to an inner edge of each lens, thus establishing the configuration of the eyewear. Because the lenses are a structural component of this type of eyewear, the attachment of the lenses to the temple pieces and nose bridge must be structurally sound. In many cases, the nose bridge and temple attachments are permanent to insure the structural integrity of the eyewear. Typically, replacement of the lenses in a three-piece frame requires the involvement of a skilled technician.
Plano lenses (lenses which do not contain specialized curvature for the correction of vision defects) for rimless frames can be manufactured efficiently with common techniques and equipment. Because there is no vision-correcting curvature in plano lenses, positioning of a lens with respect to the wearer's eyes is not critical. Accordingly, precise location of the notches is not necessary for plano lenses to serve their function as in, for example, tinted lenses for sunglasses or impact resistant lenses for safety glasses.
Prescription eyewear requires precise individualized placement of corrective lenses in the frame to achieve appropriate vision correction. In addition to cutting the lens with the proper corrective curvature, certain frame designs, such as wing style frames require lenses that incorporate the mounting system components, such as tabs or notches. Such mounting components must be accurately located on the lens to properly position the lens curvature with respect to the wearer's pupil. The cutting and preparation of such lenses for wing style frames requires a high precision, five-axis lens cutting system to properly configure the lenses. This is an expensive process requiring highly skilled technicians and specialized equipment that is not readily available in the market and is prohibitively expensive for most prescription lens makers and dispensers. Even with the most modern manufacturing techniques and equipment, the process for cutting prescription lenses with appropriate mounting elements typically results in a high percentage of rejected lenses due to limitations in materials and methods. The significant spoilage further increases costs. The adaptor of the present invention allows for more conventional equipment to be used to cut and properly align the lenses with the wearer's eyes when inserted into an eyeglass frame. If the adaptor of the present invention is used for lens mounting and frame assembly, all that the dispenser needs to do is to cut the prescription lens blank to its proper shape and desired lens centering position using conventional lens cutting techniques and equipment.
Rimless frames, particularly wing frames and those intended for athletic wear, are typically designed with complex curvatures to the brow bar. The overall contour of the eyewear imparts a sleek, aerodynamic appearance and a fashionable configuration. Lenses for such frames must have similar curvatures to insure proper fit and function and to achieve the desired aesthetics. Such lenses obviously have complex shapes at least at the interface between the lens and the brow bar. Lenses with complex curves are more difficult and expensive to produce than simpler, more generic, shaped lenses. These special shaped lenses are often special order items with significant lead times. A broken lens can cause an inconvenience for eyeglass wearers because of the delay in receiving a replacement lens.
Conversely, an inventory of the more common shaped lenses is often maintained by eye care professionals at retail locations or at optical labs, and can readily be produced. Thus, a more common shaped lens can be easily obtained, at a lower cost, for initial fitting in a pair of prescription eyeglasses or to replace missing or damaged lenses. Traditionally, these lenses have been unavailable for fitting into rimless frames or frames with more complex shapes.
Because of the difficulties in manufacturing mentioned above, the benefit of rimless frames with easily replaceable lenses have had limited availability and, when obtainable, were only available at high cost. Because of the limited availability of such lenses, an unmet need exists in many markets for easily replaceable prescription lenses for rimless frames.
Prior inventions attempted to circumvent these difficulties by providing prescription lenses attached to the back of the eyewear frame. The additional lenses added weight, complexity and compromising the aesthetics of the wing style frame. Such designs have not been widely accepted for these reasons.
Therefore, it would be an advancement in the state of the art to provide an inexpensive and efficient system for securing lenses, including in particular prescription lenses to rimless frames, wing type frames and frames of varying design and dimension, that does not require expensive and time consuming lens preparation, cutting and finishing before assembly and glazing into an eyeglass frame. It would further advance the state of the art to provide easily interchangeable lenses for rimless frames.